KR920010861B1 - Composite sintered material having sandwich structure - Google Patents

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Description

High hardness sintered composite material with sandwich structure

1 shows a cross section of a high hardness sintered composite material of the sandwich structure according to the present invention.

2 and 3 show the construction of a material filled in a capsule required for producing the high hardness sintered composite material of the sandwich structure according to the present invention.

4 shows an example in which the high hardness sintered composite material according to the present invention is used in a twist drill,

4a is a side view thereof.

4b is a front view.

FIG. 5A is a side view of the tip portion of the twist drill shown in FIG. 4,

5B is a plan view seen from the end of the drill blade.

6 shows a glass cutting tool using the high hardness sintered body of the present invention as a composite material,

6a is a side view thereof.

6B is a front view.

7 shows a wire rod roller using the high hardness sintered composite material of the present invention,

7a is a side view thereof.

7B is a front view.

* Explanation of symbols for main parts of the drawings

1: PCD 2,2 ′: support

3,3 ': middle layer 4: Co plate

5: high hardness sintered composite material 6: drill

7: beeswax

The present invention relates to a high hardness sintered composite material having a sandwich structure.

More specifically, the present invention consists of cemented carbides or metals or alloys on both sides of a diamond-based high hardness sintered compact (hereinafter, referred to as PCD), which is a material suitable as a drilling tool. It relates to a high hardness sintered composite material having a sandwich structure configured by disposing a support.

PCD is suitably used as a long-life tool, and is rapidly spreading in recent years as an indispensable material for tools for processing materials that are difficult to process. However, due to the strict manufacturing conditions, the shape of the PCD is very limited, and there is a field in which the diffusion does not extend.

In particular, in the case of a drilling tool, a drill is manufactured by inserting a PCD chip chip into a shank and attaching a blade with beeswax. After the support is bonded, it is wax-attached to the shank on the support surface. However, in the case of beeswax adhesion on one side in which a support such as cemented carbide is adhered to only one surface of the PCD piece, the beswax adhesion area is large and does not come out, and the holding strength is not sufficient. Therefore, it is desirable to adhere a support such as cemented carbide to both surfaces of the PCD piece to enable double-sided beeswax adhesion.

In addition, in the blade attachment drill, if a chip having a support bonded to only one side is used, it is necessary to position the blade so that the blade is symmetrical to the center of rotation of the tool. However, the use of a composite material having a structure in which a support having the same thickness is bonded to both surfaces eliminates the need for such complicated positioning.

However, it is difficult to manufacture a sintered composite material having a sandwich structure having supports such as cemented carbide on both sides, and therefore, drilling tools using PCD have not existed in the market.

As described above, in order to increase the holding strength of the PCD tool, a chip having a sandwiched structure sandwiching both sides of the PCD piece with cemented carbide may be considered first. For example, Japanese Laid-Open Patent Publication No. 57-66805 describes a three-layer laminated sintered body in which diamond or high density boron nitride is adhesively sandwiched between two sheet-shaped cermet small lattices. The present inventors also first test-made such a sintered composite material of the sandwich structure.

The result was that cracks arose and it was probably impossible to industrially stably produce such sandwich-shaped sintered composites.

Accordingly, it is an object of the present invention to provide a sandwich-type PCD sintered composite material having a sandwiched structure in which both sides are adhesively held by a support, which can be industrially produced stably.

Moreover, the objective of this invention is providing the sandwich type PCD sintered compact composite material suitably used as a cutting blade chip of a drill with a blade.

As described above, the composite sintered compact body sandwiched between the two sides of the PCD piece in cemented carbide was not produced industrially stably due to a lot of cracks during the sintering process. After examining the reasons in detail, the following facts were found.

In order to manufacture a three-layer high hardness sintered composite material, a diamond powder containing a mixed powder or binder pieces of diamond powder and a binder is disposed between a cemented carbide or a metal support, and sintered under ultra high pressure and high temperature to form a PCD. At the same time, the PCD and the support are bonded. However, after the end of the sintering treatment, the ultrahigh pressure is released and cooled. At this time, the thermal expansion coefficients of the PCD and the support are different and thermal stress is generated between them. Therefore, when the difference in coefficient of thermal expansion between the PCD and the support is large, the thermal stress generated between them also increases in proportion, resulting in cracking.

In the two-layered composite material in which only one support is bonded to one side, thermal stress between the PCD and the support is absorbed by the deformation of the entire material, so that no fatal cracking of the PCD itself occurs. However, in the case of a three-layered composite material in which a support body is joined to one side on both sides, a thermal expansion coefficient of the support is generally large, so that the thermal stress in the tensile direction acts on both sides of the PCD so that the PCD itself does not crack.

On the other hand, the coefficient of thermal expansion of the cemented carbide is roughly determined by the ratio of the hard phase and the bound phase contained. As the ratio of the amount of iron group metal as the bonded phase decreases, the coefficient of thermal expansion of the cemented carbide becomes smaller, which is closer to the coefficient of thermal expansion of the PCD.

Table 1 shown below shows the relationship between the Co content in the WC-Co cemented carbide and the thermal expansion coefficient of the cemented carbide.

TABLE 1

On the other hand, the coefficient of thermal expansion of the PCD is also determined by the content of the iron group metal, and increases as the Co content increases, as shown in Table 3.

TABLE 2

As described above, the magnitude of the tensile stress applied to the PCD layer is determined by the difference in thermal expansion between the PCD and the support, and the difference is usually less than 0.6 × 10 ⁻⁶ , resulting in less cracking in the PCD layer, and the sandwich structure. It has been experimentally confirmed that the high hardness sintered compact can be produced in high yield.

Therefore, when the support is a WC cemented carbide, it is necessary for the crack prevention to have a binder content of 10% by weight or less. However, in consideration of the use as a drilling tool, the Co content of the PCD layer is preferably 15 to 5% by volume in terms of cutting performance, and 5 to 2% by volume of the binder content of the cemented carbide constituting the support is appropriate. In order to reduce the coefficient of thermal expansion of the PCD layer, an iron group metal may be added to the PCD layer to contain Mo alloy and W alloy as well as Mo carbide and W carbide.

On the other hand, in the production of PCD, it is also possible to sinter only diamond particles as a starting material, but it is impossible at present to manufacture industrially excellent yields. Usually, PCD is prepared by impregnating iron group metal contained in the cemented carbide into a diamond powder during a high-pressure and high temperature treatment from a cemented carbide layer disposed adjacent to the diamond powder, or previously containing an iron group metal in the diamond powder, or The thin plate is disposed adjacent to the diamond powder, and the diamond powder is sintered by impregnating the diamond powder by dissolving the iron group metal during the high pressure and high temperature treatment.

As described above, in the structure in which the PCD is sandwiched with cemented carbide, it is necessary to lower the iron group metal content of the cemented carbide in order to lower the coefficient of thermal expansion of the cemented carbide. However, in such a case, it is difficult to supply a large amount of iron group metal to the diamond powder than the content of the cemented carbide.

That is, in order to produce a good yield of PCD, first, a diamond powder containing a sufficient amount of iron group metal should be used as a starting material.However, in the case of directly joining a diamond powder containing a large amount of iron group metal and a cemented carbide, the ultrahigh pressure and high temperature are required. During the sintering process, the iron group metal contained in the diamond powder penetrates the cemented carbide side, and as a result, the iron group metal content of the cemented carbide constituting the support with the PCD increases, resulting in a large thermal expansion coefficient of the cemented carbide, which causes the PCD layer cracking. . On the other hand, even when the amount of the iron group metal in the diamond powder is lowered and the cemented carbide having a low iron group metal content is placed adjacently and sintered, industrially high yield of PCD cannot be obtained.

According to the present invention, a high hardness sintered body layer containing diamond as a main component; The high hardness sintered compact layer is integrally bonded to both surfaces thereof, and has a coefficient of thermal expansion of 3.0 to 6.0 × 10 ⁻⁶ / ° C., a thickness of 10 μm or more and 500 μm or less, and the iron group metal is substantially formed during the sintering of the high hardness sintered compact. An interlayer not permeable; And a hardened sintered composite material having a sandwich structure, which is integrally bonded to the outer surface of the intermediate layer, and is made of a cemented carbide or metal or alloy having a thermal expansion coefficient of 6.0 × 10 ⁻⁶ / ° C. or less. do.

That is, the high hardness sintered composite material of the present invention, as shown in the accompanying Figure 1, through the intermediate layer (3), (3 ') on both sides of the PCD (1) through the support (2), (2') It is composed by bonding to one.

In addition, according to a preferred aspect of the present invention, the supports 2, 2 'are characterized by being cemented carbide containing WC and / or MoC having a coefficient of thermal expansion of 4.6x10 ^-6 / ° C or lower. As such a support, a cemented carbide is preferably composed of WC and / or MoC and the remaining components are 5 to 2 wt% Co and / or Ni.

According to one embodiment of the present invention, the supports 2 and 2 'may be a metal or an alloy containing W and / or Mo as a main component.

On the other hand, according to a preferred embodiment of the present invention, the intermediate layers 3, 3 'are nitrides, carbides, carbonitrides, borides, oxides and their mutual solid solutions of Group 3b, 4a, 4b, 5a, and 6a elements ( It is characterized by consisting of one or more selected from the group consisting of. As such intermediate layers 3 and 3 ', for example, AlN, ZrN, ZrB ₂ , HfC, Si ₃ N ₄ , SiC, ZrO ₂ , SiO ₂ , TaN, VB ₂ , V ₂ O ₃ , Cr ₃ There is C.

According to another aspect of the present invention, the intermediate layers 3 and 3 'contain 80 to 20% by volume of high pressure boron nitride, preferably 80 to 50% by volume, and the remaining components are 4a and 5a. And at least one member selected from the group consisting of nitrides, carbides, carbonitrides and borides of Group 6a elements.

Further, according to a preferred aspect of the present invention, the intermediate layers 3 and 3 'contain 80 to 50% by volume of high pressure boron nitride, and the remaining components are TiN and / or TiC or solid solutions thereof and Al, Si. It consists of sintering the mixture containing 1 or more types of.

Here, the high-pressure phase boron nitride may be either cubic boron nitride or wurtzite boron nitride.

Next, the structure of the high hardness sintered compact composite material of this invention and the reason for limitation of various conditions are demonstrated.

That is, in the present invention, as shown in FIG. 1, the iron group metal in the PCD layer 1 is supported by the support 2, 2 between the PCD layer 1 and the supports 2, 2 'with the PCD. The structure which arrange | positions the intermediate | middle layers 3 and 3 'is adopted in order to prevent penetration to the side of'. That is, the coefficient of thermal expansion of the PCD 1 is 3.5 to 4.0 × 10 ⁻⁶ / ° C. as described above, and as shown in Table 1, Co-containing WC, which is frequently used as an example of the supports 2 and 2 ′. The thermal expansion coefficient of -Co cemented carbide needs to be as close as possible. It is preferable that the intermediate layers 3 and 3 'also approximate the thermal expansion coefficients of both the PCD 1 and the supports 2 and 2'.

Therefore, as a characteristic suitable for the intermediate | middle layers 3 and 3 ', it is necessary that a thermal expansion coefficient is 3.0-6.0 * 10 <^-6> / ^degreeC . Largely out of this range, the residual stress between the PCD (1) and the intermediate layers (3), (3 '), the intermediate layers (3), (3') and the supports (2), (2 ') is the bond strength of the interface. Or greater than the breaking strength of the material of the intermediate layers 3 and 3 ', thereby destroying the sandwich structure.

Further, when the contact angle between the liquid of the iron group metal or the alloy and the intermediate layers 3 and 3 'is close to zero or zero, the iron group metal contained in the diamond powder during sintering is the intermediate layer 3, 3 ') Or through the intermediate layers (3) and (3') to reach the support to increase the content of iron group metals in the supports (2) and (2 '), thereby increasing the coefficient of thermal expansion. The residual stress between 1) and the support 2, 2 'becomes large, which leads to the destruction of the sandwich structure.

Therefore, during the sintering, the movement of the iron group metal from the diamond powder 1 constituting the PCD to the materials 2 and 2 'of the support is effectively prevented, and the PCD having a desired iron group metal content, that is, mutually close thermal expansion coefficient. In order to obtain (1) and the supports 2, and 2 ', it is necessary to use intermediate layers 3 and 3' made of a material having a characteristic in which the contact angle with the iron group metal or the molten metal of these alloys is 20 ° C or more. Do.

Using such an intermediate layer has the effect that the molten metal of the iron group metal or alloy thereof does not substantially pass through the intermediate layer.

The thickness of the intermediate layers 3 and 3 'being 10 µm or more and 500 µm or less is insufficient to prevent the penetration of the iron group metal from the PCD 1 to the supports 2 and 2' at 10 µm or less. .

In the present invention, the purpose of interposing the intermediate layers 3 and 3 'between the supports 2 and 2' of the PCD 1 is to provide a thermal expansion coefficient of the supports 2 and 2 'as much as possible. This is to support the movement of the iron group metal from the PCD 1 to the supports 2, 2 'during the sintering in order to be close to (1). Therefore, the thickness does not have to be 500 µm or more. In addition, when the intermediate layers 3 and 3 'are thickened, the influence of the thermal stress between the PCD 1 and the supports 2 and 2' becomes large, which causes deformation or cracking of the whole composite material. That is, in the present invention as described above, the support 2, 2 'of the PCD 1 is preferably made of a material whose thermal expansion coefficient is as close as possible, but the thickness of the intermediate layers 3, 3' is The larger the coefficient of thermal expansion of the intermediate layers 3 and 3 'itself, the larger the coefficient of thermal expansion of the PCD 1 and the supports 2 and 2', and therefore the narrower the material selection.

In the case where the thicknesses of the intermediate layers 3 and 3 'are 500 µm or more, when the high hardness sintered composite material having a sandwich structure is brazed to other machined parts, the intermediate layer having poor electrodeposition with the solder material ( 3), (3 ') may be exposed.

As mentioned above, although this invention was demonstrated about using cemented carbide as support bodies 2 and 2 ', W, which has a small coefficient of thermal expansion as a metal or an alloy, or heavy metal etc. which have W as a main component etc. are also used as support body 2, ( 2 ') is suitable.

The following examples illustrate the effects of the invention.

Example 1

The laminated structure is filled with a diamond powder (1) containing iron group metal in advance, and intermediate layers (3), (3 '), supports (2), and (2') on both sides thereof in a capsule as shown in FIG. Sintering is performed at 55,000 atmospheres and 1,400 ℃ using an ultra high pressure and high temperature device.

The composition of the obtained super-strength sintered composite material and the observed crack occurrence state are shown in Table 3.

In the sandwich-type superhard composite material tested as described above, in the composite material having the intermediate layer of the present invention, the cobalt (Co) distribution state of the intermediate layer disposed between the PCD layer and the support layer was analyzed using an X-ray trace analyzer ( XMA) showed that the cobalt of the intermediate layer was much smaller than the amount of cobalt present in the PCD layer, and the cobalt did not actually move from the PCD layer to the support layer through the intermediate layer.

[Table 3]

Example 2

As shown in Fig. 3, a 4% Co-WC alloy having a diameter of 30 mm and a thickness of 3 mm, which was coated with 60% CBN + TiN powder (constituting the intermediate layer 3 ') in order from the bottom [support 2 ′); 2 g of diamond powder having a particle size of 5 to 10 mu (which constitutes the PCD 1); A Co plate 4 having a diameter of 30 mm and a thickness of 200 mu (which becomes a binder of the PCD 1); 4% Co-WC alloy [support body 2 having a diameter of 30 mm and a thickness of 3 mm, which has a 60% CBN + TiN powder coated surface (constituting the intermediate layer 3) on the lower surface and arranged to be in contact with the Co plate 4. ), And then, the whole of them are filled in a protective capsule which can be made of a high melting point metal, held at 1,400 ° C. and 55,000 atmospheres for 15 minutes in an ultra-high temperature and high temperature apparatus, and then taken out.

As a result of observing the obtained high hardness sintered composite material, no crack was found in any high hardness sintered composite material. In addition, the high hardness sintered composite material was divided and its cross section was observed by an optical microscope. The 200-μ-thick Co plate 4, which was disposed for the purpose of the binder and the catalyst, was dissolved to fill the gap between the diamond particles. It was confirmed that Co hardly penetrated the 60% CBN + TiN layer applied as the intermediate layers 3 and 3 '.

Example 3

The experiment was carried out in the same manner as in Example 1 using a diamond powder for PCD, an alloy for a support, and an intermediate layer material whose composition is as shown in Table 4 and whose average particle size was about 4 µm. The crack occurrence condition as described in the following was observed.

[Table 4]

In addition, a twist drill having a hole diameter of 6 mm as shown in FIG. 4 was produced from the sandwich type sintered bodies obtained in A to F, mounted on a drilling machine, and then drilled at 20,500 Si-Al alloy at 1,500 rpm. The test was done. As a result, the twist drills obtained from the sintered bodies of A, B, D, and F require a change of the drill due to the increase in the diameter of the hole from 50,000 to 75,000 hits, whereas the drills need to be replaced at 20,000 hits in D and 5,000 hits in C. I need to do it.

Example 4

A diamond powder having a particle size of 1 to 20 µ, in which a laminated structure is mixed with an alloy powder of 5% Fe-45% Ni-50% Co as a PCD layer 1 in advance in a capsule as shown in FIG. 1, Intermediate layers (3) and (3 ') on both sides thereof as the main component of high-pressure boron nitride, and the remaining components are mixed powders consisting of the components of the fifth table, and retardation materials (2) and (2') on both sides thereof, 5% by weight. The WC-Co alloy containing Co was filled and then sintered at 55,000 atmospheres and 1,400 ° C using an ultrahigh pressure high temperature apparatus. As a result of inspecting the obtained high hardness sintered composite material, no crack was generated in the PCD layer in any kind of intermediate layer.

[Table 5]

Example 5

As shown in FIG. 3, the laminated structure is shown in FIG. 3, and in the capsule having an inner diameter of 30 mm, the 10 wt% Co-WC cemented carbide as the PCD layer 1 contains 10 wt% of fine powder (particle diameter of 1 to 2 μ). 2.0 g of a mixed powder having a particle size of 1 to 10 diamond, and 0.2 g of a Co plate having a thickness of 0.2 mm and 0.25 g of 60 vol% CBN-40 vol% TiN as intermediate layers 3 and 3 'on both sides thereof. A disc of 30 mm in diameter and 3 mm in thickness consisting of 4 wt% Co-WC alloy as support 2 and 2 'on both sides thereof was placed, and then they were loaded into a girdle type ultra high pressure generator. Subsequently, the mixture was kept at 50 kb and 1,500 ° C. for 15 minutes, and then taken out. As a result, a sandwich-type sintered composite material having a layer height of 65 mm and an outer diameter of 30 mm without cracks was obtained.

Example 6

In a capsule having a laminated structure as shown in FIG. 3, 3 g (1) of diamond powder having a particle size of 1 to 20 µm and a mixed powder (3) or (3 ') consisting of 60 vol% CBN and the remaining components of TiN are methylated. After mixing with alcohol, it was about 30 mm in diameter and 3 mm thick, consisting of (MoW) C as the main ingredient and the remaining components consisting of 3% by weight Co + 2% by weight Ni (2), (2 ') 0.2g is apply | coated and laminated | stacked as shown in FIG. This was charged into an ultrahigh pressure high temperature apparatus, pressurized and heated at about 55 kb and 1,400 ° C., and then taken out to obtain a high hardness composite sintered compact having a sandwich structure without cracking.

As described above, the present invention has succeeded in providing a high quality sintered composite material of high quality, which has a large adhesive area with a tool support, free from cracks, and the like. It is suitably used as a hard blade material of a drilling tool such as.

4 shows a state where the high hardness sintered composite material 5 of the present invention is formed into a long term shape and is cut at the tip of the twist drill. A method of processing the high hardness sintered composite material 5 of the present invention on the distal end of the twist drill and processing the drill with a blade with reference to FIGS. 5A and 5B will be described.

FIG. 5A is a side view of the tip portion of the twist drill shown in FIG. 4, and FIG. 5B is a plan view seen from the end of the drill blade.

The wax 7 is applied to the groove of the blade formed at the tip of the drill 6, and the high hardness sintered composite material 5 of the present invention cut into a long horse is press-fitted therein. Subsequently, as shown in FIG. 5B, the intermediate layer of the support is surface cut to expose the surface layer of the PCD 1, and the cutting surface is symmetrically formed at the center of the drill rotation.

Using the high hardness sintered composite material 5 of the sandwich structure of the present invention shown in FIGS. 5A and 5B, it is easy to determine the position of the cutting surface 1 symmetrically with respect to the center of rotation of the drill, The high load during cutting acts on the drill body symmetrically through the supporting layers 2, 2 'and intermediate layers 3, 3' as shown in FIG. 5B, thus cutting at a much higher speed than conventional rotary drills. can do. In addition, since each cutting surface is composed of one high hardness sintered composite material 5, the influence of the load during cutting is further reduced.

The high hardness sintered composite material 5 of the present invention can be used not only for the twist drill but also for the blade of a straight tooth drill.

In addition, the high hardness sintered composite material of the present invention is not limited to a drilling tool, and is preferably used as a material for glass cutting tools, wire rolling rollers, etc., in which it is desirable to increase the bonding strength with the tool support.

6 and 7 show examples in which the high hardness sintered composite material of the present invention is used for a glass cutting tool and a wire rod roller.

FIG. 6 shows the whole glass cutting tool composed of the high hardness sintered composite material of the present invention, and FIG. 7 shows the ball roller for the wire rod in which the ball portion is composed of the PCD.

As described above, the high hardness sintered composite material of the present invention has various uses and its industrial value is large.

Claims (12)

A layer of high hardness sintered body composed mainly of diamond; It is bonded to both surfaces of the said high hardness sintered compact layer one, the thermal expansion coefficient is 3.0-6.0 * 10 <^-6> / degreeC, thickness is 10 micrometers or more and 500 micrometers or less, and it permeate | transmits iron group metal substantially in the middle of sintering a high hardness sintered compact. Intermediate layer which does not make it; And a support made of cemented carbide or a metal or an alloy having a coefficient of thermal expansion of 6.0 × 10 ⁻⁶ / ° C. or less, each bonded to the outer surface of the intermediate layer, wherein the high hardness sintered composite material having a sandwich structure. The method of claim 1, wherein the high hardness sintered body contains 5 to 15% by volume of the iron group metal and the remaining components thereof are diamond particles, the support is a main component of WC and / or MoC with a coefficient of thermal expansion of 4.6 × 10 ^-6 / ℃ or less Hardened sintered composite material characterized in that the cemented carbide 3. The high hardness sintered composite material according to claim 2, wherein the support contains 5 to 2% by weight of Co and / or Ni, and the remaining components thereof are cemented carbide of WC and / or MoC. The method according to any one of claims 1 to 3, wherein the intermediate layer is at least one selected from the group consisting of nitrides, carbides, carbonitrides, borides, oxides, and their mutual solid solutions of elements 3b, 4a, 4b, 5a, and 6a. High hardness sintered composite material, characterized in that made. The method according to any one of claims 1 to 3, wherein the intermediate layer is composed of 80 to 20% by volume of high-pressure boron nitride, and the remaining components thereof are nitrides, carbides, carbonitrides, borides and the like of group 4a, 5a, and 6a elements. A high hardness sintered composite material, characterized in that it consists of one or more selected from the group consisting of these mutually solid solutions. 6. The high hardness sintered composite material according to claim 5, wherein the intermediate layer contains 80 to 50% by volume of high pressure boron nitride. The method of claim 6, wherein the intermediate layer is composed of 80 to 50% by volume of the high-pressure boron nitride as a main component, and the remaining components thereof are sintered a mixture containing TiN and / or TiC and their solid solutions and at least one of Al and Si. High hardness sintered composite material characterized in that. The high hardness sintered composite material according to claim 1, wherein the support is a metal or an alloy containing W and / or Mo as a main component. The method of claim 8, characterized in that the intermediate layer is made of one or more selected from the group consisting of nitrides, carbides, carbonitrides, borides, oxides, and their mutual solid solutions of Group 3b, 4a, 4b, 5a, and 5b elements. High hardness sintered composite material. 9. The intermediate layer of claim 8, wherein the intermediate layer is composed of 80 to 20% by volume of high-pressure boron nitride, and the remaining components thereof are nitrides, carbides, carbonitrides, borides, and their mutual solid solutions of Group 4a, 5a, and 6a elements. High hardness sintered composite material, characterized in that consisting of at least one selected from the group consisting of. The high hardness sintered composite material according to claim 10, wherein the intermediate layer contains 80 to 50% by volume of high-pressure boron nitride. The sintering process according to claim 11, wherein the intermediate layer is composed of 80 to 50% by volume of high-pressure boron nitride, and the remaining components thereof are sintered mixtures containing solid solutions of TiN and / or TiC and at least one of Al and Si. High hardness sintered composite material characterized in that.

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